Fixed temperature responsive device



June 12, 1945. E N 2,378,135

FIXED TEMPERATURE RESPONSIVE DEVICE Filed A rii 1S, 1939 'INVENTOR F. c.; EVANS I ATTORNEY Patented June 12,1945

FIXED TEMPERATURE nusronsrvr: DEVICE Francis 0. Evans, Dongan Hills, N. Y., assignor to American District Telegraph Company, Jersey City, N. J a corporation of New Jersey Application April 15, 1939, Serial No. 261,905

4 Claims. to]. 111-355) This invention relates generally to fire detecting systems of the fluid expansion typewhich are responsive to dangerous temperatures. The invention relates more particularly to systems utilizing aero-tubing for detecting dangerous rises in temperature and also includes attachments for detecting fixed temperatures regardless of the rate of rise thereof. I

This type of system is sometimes required where abnormally high but safe temperatures occur such as in factories where furnaces create high ambi-- ent temperatures which do not mean that a fire condition exists. This situation also arises in bakeries, forge shops and various other enclosures where local heat sources cause extreme changes of'temperature. In these particular enclosures. the aero'tube system operating on the rate-ofchange principle may be used for detecting dangerous temperatures in a large part of the enclosure but in local areas such asv those around a furnace or even it is necessary to use a fire de-v tecting device which operates at a fixed temperature regardless of the rate of rise thereof.

\ Fixed temperature detecting devices for use in connection with the aero-tube systems have been suggested in the prior art but they do not meet achange in the operating characteristics of, said I system whena leak in the attachment occurs.

Still anotherobject of this invention is to provide an improved fire detecting attachment for use in aero-tube systems which generates andreleases a pressure impulse at a fixed temperature regardless of the rate of rise thereof- A still further objector this invention is to provide a. fire detecting attachment for aero-tube systems which operates. at a fixed temperature and which does not disable the aero-tube system either when said attachment operat es or when a simplify the construction of fixed temperature the requirements of a safe fire detectionsystem. In the first place, these attachments should not change the volume of the aero-tube system to such an extent that its'operating characteristics are changed, or to the extent that the amount ofarea or number of enclosures which an acre tube circuit can safely cover is reduced. If the attachments develop leaks or if they operate'to detect a fire. they must not disable the system or change its operating characteristics to such an extent that a fire may occur without an alarm being given. Furthermore, the previous attachments suggested in the prior arthave been of complicated structure and expensive to manufacture.

Accordingly the principal object of this invention is to provide an attachment adapted-for use in a rate-of-rise-of-temperature detecting system for actuating said system at a fixed temperature regardless of the rate of rise thereof.

A further object of this invention is to provide an attachment for an aero tube system which is adapted to detect a fixed temperature regardless oi its rate ofrise without affecting the rateoi-rise characteristics of said aero-tube system.

Another object of this invention is to provide a fixed temperature detecting device in an aerotube system which does not cause a leak in, or,

fiuid pressure generating devices for use in areotube systems. t

Further objects and advantages of this invention will be Obvious to those skilled in the art from an inspection of the following specification and the accompanying drawing wherein:

Fig. 1 illustrates an aero-tube system including a cross-section of the preferred embodiment of a fixed temperature detecting device constructed in accordance with this invention;

Fig. 2 is aplan view of. a modification of the detecting deviceshown in Fig. 1 with parts cut away to show other parts in section;

Fig. 3 is a plan view partly in section of another modification of this invention;

Fig. 4 is a still further modification of this invention showing parts thereof in section; and

tions arise within enclosures such as factory I high and extremely sudden temperature changes. Such changes of temperature normally cause false alarms ii the usual aero-tubesystem is used for fire detection, but by adding a fixed temperature detecting device constructed in accordance with this invention for the protection of areas in the proximity of furnaces or ovens suitably insulating the adjacent aero-tubing, false alarms may be avoided without jeopardizing fire protection or response to actual fire occurrence in the premises.

1 This invention may also be ap lied where only a fixed temperature detecting system is desired by using acre-tubing for connecting a number of detectors together and to a central point. In this type of system the aero-tube may be insulated or otherwise protected from ambient temperature changes so that an alarm occurs at a fixed temperature regardless of the rate of rise thereof.

Fig. 1 of the drawing shows a fixed temperature detecting device for use in aero-tube systems such as that shown by and for the same purpose as described in the patent to F. M. Cowan, No. 2,100,183. This device is connected to the conventional system and consists of a cylindrical heat-collecting member I having heat-collecting fins 2 thereon and supported from the ceiling or wall 4 of-an enclosure by the supporting member 6. ,The upper end or cylindrical'member I is closed by a cover member I, having a tubular ex- 1 or its equivalent, against the lower extremities of tube 8 whereby a firm support is obtained. The sealed chamber thu formed within the tubular member i0 communicates with the aero-tube system 5, which is arranged in the conventional manner, through the passage Ill within the cover I4 and the integral T member I8 whereby changes in pressure within the chamber are transmitted to the detecting element 3 which is connected to the aero-tube' system 5 and which causes an alarm. It is to be understood any desired number of these devices may be connected in the system 5. The spring member I8 is attached at one end to the cylinder member I. by means of the solder 20 which is responsive to or melted at agiven fixed temperature while the other end of spring member I8 is attached to the element 1 by means of a suitable fastening means such as a rivet, a welded joint or by solder 2| which may be responsive to a fixed temperature which is higher than that to which the solder 20 responds. The spring I8 is afiixed at one end to member I by solder 2I and then deformed by attaching the other end to member I by solder 20. A puncturing spike 23 is attached to the spring I8 for the purpose of puncturing the foil I2 when solder 20 is melted in renal shapeand forces the puncturing spike 23 topierce the foil I2 thereby releasing the accumubuildings where furnaces or ovens cause extremely lated pressure and causing a considerable increase in pressure within the tubing 5 which in turn causes a fire alarm to be sounded.

It should be noted that the foil I2 normally seals the aero-tube system from the air chamber within the tubular member I so that the normal volume of air enclosed in the tubing 5 is changed very little by connecting the fixed temperature device thereto. This is an important feature of the invention since the operating characteristics of the aero-tube system as a whole are changed very slightly if at all when one or a considerable number of the fixed temperature attachments are connected in the aero-tube system. It should further be noted that leaks in the outside heat collecting element I cannot affect the operating characteristics of the acre-tubing circuit, since the foil I2 completely seals the aero-tube circuit. Therefore, even though one or more of the fixed temperature attachments may have leaks therein, the entire aero-tube'circuit is in its normal operating condition.

Fig. 2 illustrates an alternative method of releasing a pressure impulse from the cylindrical chamber I when the predetermined operating temperature melts the solder 20. The spring member I8 operates a mechanical linkage 28 which forces the valve member 32 against the spring 3 to allow the passage of a pressure impulse through the passage 38 and to the aero tube system in the same manner as illustrated in Fig. 1. Valve member 32 cooperates with a seat formed interiorly of externally threaded tubular member 30, the upper end of which is threaded into an enlarged portion of a fitting 3|, the bore I8 01 which communicates with a member similar to member IQ of Fig. 1. This form of releasing member presents the same advantages as those shown in Fig. 1 except for the added advantage that the valve structure can automatically reseal the air chamber after solder 2| is melted. Thus the volume of the aero-tube system is not increased by the operation of a, detecting attachment.

Fig. 3 shows still another modification of the invention having a slightly different structure in that shown in Fig. 2. Disc 43 flexes at a predetermined temperature to force the valve 32 to an open position and release apressure impulse. When the temperature falls to normal, the disc 43 automatically restorespthe valve 32 to its closed position so that manual restoration is not necessary.

Fig. 4 shows a similar construction with the exception that the 'bi-metallic member 43 operates a puncturing device 23 which punctures the foil I2 to release accumulated pressure at a critical temperature Within the chamber 4|.

Fig. 5 shows a form of the invention involving a means for mechanically creating a pressure pulse within the areo-tube system. This mechanical operation is accomplished by utilizing a bellows 45 supported within a framework 40 and operated by a-bi-metallic disc 4! supported on the adjustable stop member 48 and connected to the bellows 45 through the lugs 50. Bellows 45 operates valve stem 49 of valve 5| which is of the same type as the valves sho'7n in Figs. 2 and 3. When a predetermined temperature occurs the bimetallic disc flexes and compresses the bellows .45 thereby creating pressure which may be resive devices are capable of only one operation since the foil of Figs. 1 and 4 and the spring 8 of Figs. 1 and 2 must be restored to operative condition. In order. to quickly locate the particular detecting device which operated in response to a dangerous fire condition, a spot of wax is placed within the indentation 21 on the lower face of the cylindrical member I, see Figs. 1 and 2. The lower face of the cylindrical member I may be stamped with a star-shaped pattern or with any other pattern to provide small indentations such as 25 and 26 which communicate with the indentation 21. Thus, when a high temperature occurs the wax normally located within the indentation 21 will flow through the indentations 25 and 26 by capillary action and subsequently harden thereby providing a visible indication of the inoperative condition of the particular detecting device which has operated to cause an alarm. This saves a practically complete repair of a large number of the detecting units within a given aero tube circuit in order to locate the operated detecting unit.

.From the above description, it is evident that the fixed temperature detecting device may be connected to an aero-tube system of the conventional type without changing the operating characteristics thereof. In each of the modifications of this invention the heat collecting chamber is completely sealed from the a remainder of the aero-tube circuit whereby leaks in the attachment itself do not affect the operating characteristics of the entire system.

Further modifications of this invention will be evident to those skilled in the art and therefore I desire that this invention shall be limited only by the prior art and the appended claims.

I claim:

1. A fixed temperature fire detecting device comprising a cylindrical heat collecting member having a closed end and enclosing a chamber, fins supported on the outside wall of said member for enhancing the heat collecting properties of said member, a tube extending into said chamber for conducting pressure pulses therefrom, a metallic foil for sealing the end of said tube, a

sharp member adjacent the foil for puncturing said foil and means for operating said sharp member comprising a spring member fastened to the closed end of said chamber by solder of predetermined melting point whereby a predetermined temperature causes release of said spring member and release of the accumulated pressurewithin said chamber.

2. A fixed temperature fire detecting device comprising a cylindrical heat collecting member having a closed end and enclosing a chamber, a tube extending into said chamber for conducting pressure pulses therefrom, a metallic foil for sealing the end of said tube, a sharp member adjacent the foil for puncturing said foil and means for operating said sharp member comprising a spring member fastened to the closed end of said chamber by solder of predetermined melting point whereby a predetermined temperature causes releaseof said spring member and release of the accumulated pressure within said chamber.

3. A fixed temperature fire detecting device comprising a cylindrical heat collecting member having a closed end and enclosing a chamber, a metallic foil for sealing the chamber, a sharp member adjacent the foil for puncturing said 30 011 and means for operating said sharp member comprising a spring member fastened to the closed end of said chamber by solder of predetermined melting point whereby a predetermined temperature causes release of said spring member and release of the accumulated pressure within said chamber.

4. A fixed temperature fire detecting device comprising a cylindrical heat collecting-member having a closed end and enclosing a chamber, a

metallic foil for sealing the outlet of said chamber, a. puncturing member adjacent the foil adapted to rupture satd metallic foil and means comprising a spring member fixed to the end of saidchamber by solder of predetermined melting ll point for releasing said puncturing member at a predetermined temperature to release the accumulated pressure within said chamber.

FRANCIS C. EVANS. 

